Accidental Ladder Test

[JohnyRingo]

After buying a new 300 H&H Mag with a detachable magazine, I realized all the handloads from my previous rifle were way too long to be used in this new rifle. I then started over with a new load and because I am no expert, I started messing with the COAL and .5 grain powder increases. I began by loading the cartridge as long as I could for it to just fit inside the detachable box magazine because the recoil was messing with the ballistic tips I was shooting. I now know that I should have begun with finding the lands length first, but I didn't.

I then started quite bit lower in powder than my previous loads because the bullet was seated deeper. I did shoot through a chrono and noticed that for every .5 grains I added, there was considerable jump in velocity until I got to around 2950 fps, which is the velocity I was trying to get to. I then noticed that adding a half grain did not increase the velocity much. At the time, I figured I was at the point of diminishing returns and getting close to max load, so I stopped at the powder load that resulted in the last substantial velocity jump.

Now that I have researched this topic a little better, should I have used the next .5 grain powder charge instead because it represented a velocity node and maybe a little better accuracy? I am still messing with the accuracy of this rifle because I feel the cheep stock is the result of the 1 moa that it currently shoots versus 1/2 moa. I have a McMillan stock that should be here in about another 2 months.

When the weather gets a little nicer, I plan on figuring out the distance to the lands and then revisiting the ladder test. After I figure out the velocity and accuracy sweet spot, I plan on messing with the seating depth a little to further improve the accuracy. Does this sound like I am headed in the right direction? I have a buddy who wants me to develop a load for his 300 WinMag when he gets it, not because I am an expert. It's just because I know a little more than he does about the topic. I just don't want to mess up his new gun.

 

[Dzel777]

I’ll take a shot..
not an expert at all, I think very few can make that claim when it pertains to such a scientific art as reloading

If it were my time and money I would simplify and streamline your process, and start over from the beginning.
In my opinion if you are attempting a ladder test to find a node it should be done on paper and at the longest distance you feel confident in your ability shooting less then moa.
I’ve refined my process over the years and it works very well. Generally two- three sessions and I have a load that’s sub 1/2 moa, I stop there and start shooting, or tune until half my barrel is gone

Step one:

Barell break in is first, follow manufacturers recommendations and don’t skip this step.

Two: find Cartridge base to ogive measurement.
Perfectly prep quality brass, donate 20 or so pieces to load work up and only use those 20 pieces for this ENTIRE process (they should be brand new to start)
ALWAYS completely prep brass when loading a new test batch, I realize that you might got 2-5 loadings in between trimmings but now everything must be as perfect as possible!

Load groups of 5 rounds in 1 grain increments, I start in the lower middle of a know powder range and work up. Example: if book range is 70.0-76.0gr, I would load 5 rounds @ the following: 73, 74, 75. All loads would be seated .010” off lands.
Shoot three shot groups with each, I’ll chrono two shots of each to see where I’m at.

This is where you can accomplish one of the same goals as a ladder test on paper;
You will see that most magnum rifles have a 2-3 grain window where they are accurate and in the ballpark of the speed you are looking for.
I opt to load in the middle of one of these windows, this gives my load the best chance to be accurate in very cold or very hot temperatures.

Sometimes you will get lucky and a simple powder test is all you need. Sometimes it will get you close but not quite there. When that happens I pick a charge that’s in the middle of an accuracy node and do a bullet seating depth test. Standard Berger style is great.
After this it if you would like to do a ladder test to confirm or to hone in on a node;
.5gr increments starting from lowest charge that will suffice for speed going to max charge. 1 shot each on target and you will see what a ladder test really does, remember the further the better!
Generally there will be a 1-2.5gr window where a few of the shots will land on top of each other and the vertical climbing ends. This would be your node.
As far as finding max charge, this should not be done with a chrono because it is not a factor of speed but much more importantly pressure. Pressure signs and signals should Be monitored throughout the entire process.
It is very possible to be well below max charge and no longer see your speed climbing at a steady rate, this Generally means you are no longer getting a good powder burn, too much powder and not enough Barell.
Hope that helps and wasn’t too long winded! Lists to cover.
Cheers!